Casing cleaning device



1968 w. s. TOMPKINS CASING CLEANING DEVICE 2 Sheets-Sheet 1 Filed Jan. 10, 1966 WILLIAM S. TOMPK/NS M/VENmR ,477'ORNEVS Unitd States Patent 3,381,754 CASING CLEANING DEVICE William S. Tompkins, 275 Las Flores Drive, Bakersfield, Calif. 93305 Filed Jan. 10, 1966, Ser. No. 519,498 9 Claims. (Cl. 166170) ABSTRACT OF THE DISCLOSURE The invention consists of an electric motor in a housing from which a shaft rotatably driven by the motor extends, a plurality of holders arranged radially around the shaft and pivoted thereto for swinging radially outwardly in response to centrifugal force resulting from rotation of the shaft, each holder having secured thereto a stiffiy resilient member the outer end of which carries cleaning means brought into cleaning engagement with a casing wall by outward swinging of the holder. In one form, the stiffly resilient member is a metal cable; in another, a spring carrying a star wheel. The housing is prevented from rotating by star wheels gripping the casing wall and continuously urged into gripping engagement by radially acting springs.

The present invention relates to a casing cleaning device and more particularly to such a device adapted to be lowered into an oil well casing or the like and to be rotated in such a casing so as to cause said device by centrifugal forces to spread radially outwardly into cleaning' engagement with the casing.

While the device of the present invention is suited for use in innumerable objects having bores or openings defined by surfaces of revolution, it is particularly useful in the cleaning of Well casings and will be described in connection with such an environment for illustrative convenience.

During the normal functioning of an oil well, oil and other liquids percolate through the surrounding strata into the bottom of the well, where they generally form a pool. Additional oil from the strata tends to seep into the well through perforations provided in the casing wall and to flow down the casing Wall into the pool. After a period of extended operation, the oil tends to solidify and to clog the perforations in the wall, thereby reducing the operative efficiency of the well. Furthermore, during percolation of the oil and other liquids through pores in the strata, relatively heavier tars and residues tend to remain behind in the strata where they evenually clog the pores and reduce the flow of oil into the well until it is no longer economically feasible to maintain the well in operation.

Various methods have previously been employed for removing oil deposits and other residue from casing walls. Such methods have frequently involved the application of rotary brushes advanced progressively along the length of such a wall. This procedure has certain disadvantages, one being that it is often difficult to manipulate a cleaning brush effectively in a deep well, since a tight fit is necessary in order to give effective brushing contact with the wall. This factor effectively limits the optimum efficiency achievable with conventional brushes, since if a large enough brush is used to provide the desired tightness of fit, the brush is often unmanageable while disposed in the casing. This is especially a draw-back in the cleaning of casings having perforations, since brush bristles cannot be long enough to extend into the perforations with any degree of forcefulness and still be operative. Also, it is difiicult to rotate a tightly fitting brush at a sufficiently high speed to permit the cleaning operation to be performed in a reasonably short length of time withice out causing damage to the brush. Although various cleaning agents or luqiids, such as water, solvents, acids, and the like, have been used to augment the cleaning action of the brushes, the full potential of such agents has not previously been attained, due to the above speed limitations and tightness of fit required of conventional brushes.

Therefore, it is an boject of the present invention to provide a casing cleaning device which may be lowered into an elongated casing of an oil well or the like for cleaning the casing wall.

Another object is to provide such a cleaning device which is operable in boreholes and other openings defined by the surfaces of revolution.

Another object is to provide such a cleaning device which is characterized by a high degree of adaptability in accommodating radial variations in such boreholes or the like.

Another object is to provide such a device which may be easily and conveniently manipulated within such a casing to allow thorough and efficient cleaning thereof progressively along its length.

Another object is to provide such a device which may be operated at sufficiently high speeds to expedite the cleaning process and thereby to reduce the shut-down time of a well to a minimum.

Another object is to provide such a device which may be used with cleaning agents such as acids, solvents or the like and which is adapted to promote circulation of such agents against the casing wall and into neighboring oil bearing strata.

Another object is to provide such a device which forcefully engages the casing wall during cleaning while being adapted freely and without excessive resistance from the casing wall to be selectively lowered and raised in said casing.

Another object is to provide such a device which is adapted during operation forcefully to project into perforations in the casing wall so as to clean deposits and the like from said perforations.

Another object is to provide such a device having a relatively simple design and a minimum of parts, said parts, being adapted to be replaced conveniently and economically.

These and other objects will become more fully apparent in the following description and accompanying drawings.

In the drawings:

FIG. 1 is a side elevation of one form of casing cleaning device embodying the principles of the present invention in operational position in a well casing shown in longitudinal section.

FIG. 2 is a horizontal section of the device of FIG. 1 taken in a plane represented by line 2-2 of FIG. 1.

FIG. 3 is an enlarged isometric view of a cleaning assembly forming a portion of the device of FIG. 1.

FIG. 4 is a somewhat enlarged fragmentary side elevation of the device of FIG. 1, showing a casing gripping member engaged with the casing, the latter being shown in longitudinal section.

FIG. 5 is a side elevation of the device of FIG. 4 showing a front view of the casing gripping member.

FIG. 6' is an enlarged side view of a second form of cleaning member adapted to be used with the present invention.

Referring more particularly to the drawings, a partial view of an oil well casing 10' is shown in FIG. 1. The casing has a wall 11 with a plurality of louvered perforations 12 therein to permit oil from surrounding strata, not shown, to enter through the perforations and flow down the wall into the bottom of the oil well.

A casing cleaning device embodying the principles of the present invention is shown generally at 13 suspended in the casing 10. The device includes a fluidtight housing 14 having a base 15, top 16, and side wall 17. A handle is secured to the top of the housing and includes uprights 21 and a crossbar 23 joining the two uprights. A cable 24 is attached to the crossbar and extends to the ground surface above, where it may be suitably connected to a winch, not shown, used for raising and lowering the device within the casing. A suitable power driven means such as an electric motor 25 is mounted on the base inside the housing. Electrical leads 26, passing through a fluid-tight plug 3i), connect the motor to a source of electric power, not shown, at the top of the well. The motor has a drive shaft 31 which extends through the base of the housing in fluid-sealing relation therewith. The shaft has an internally threaded end 32.

A suitable cleaning assembly adapted to be connected to the shaft 31 and providing individual cleaning members 34 for cleaning the casing wall 11 is shown generally at 33. The assembly includes a shaft 36 provided with an externally threaded end 37 which is secured to the threaded end 32 of shaft 31, as shown in FIG. 1. Although any suitable form of mounting may be utilized for the individual cleaning members of the assembly, in the illustrative embodiment, each mounting consists of a pair of spaced parallel mounting bars 40 attached substantially at their midpoints to shaft 36 by a bolt 46. The shaft may be indented to provide secure seats for the respective bars. A plurality of such mounting-bar pairs are spaced along shaft 36 longitudinally of its axis of rotation and extending transversely thereof. Each pair of bars is positioned preferably in substantially perpendicular relation to the adjacent pair. Elongated holders 51, forming portions of the cleaning members 34, are pivotally mounted at one end on bolts 52, which connect the radially outer ends of each pair of mounting bars and permit the respective holders to pivot freely outwardly from shaft 36. The free end of each holder accommodates a stiffiy resilient steel cable brush 53.

A second form of cleaning member adapted to be used with the present invention is illustrated at 54 in FIG. 6. It includes a holder 55, a stifily resilient spring 56 mounted at the end of the holder and a toothed member such as a star-wheel 57 mounted on a coupling 58 for free rotation at the end of the spring. The holder is pivotally mounted on a bolt 52 for radially outward pivotal moveent as with the first form.

When the cleaning members 34 or 54 are rotated in engagement with the casing wall 11, a substantial turning force is transmitted to the housing 14, which, if not Y counteracted, causes the housing to rotate and twist the cable 24. To prevent this from occurring, a pair of leaf springs 65 are mounted on the respective opposite sides of the housing. Each leaf spring is provided with an end slot 67 and a medial slot 68, as shown in FIG. 5 Each spring is bolted at both ends to the side wall 17, one end being disposed adjacently of the base 15 and the slotted end being disposed adjacently of the top 16. The slotted end is adapted to reciprocate slidably on its bolt. The leaf springs are sized so as to be biased outwardly into grip ping engagement with the casing wall 11. This outward bias may be augmented by compression springs 71, suitably mounted between the leaf spring and the side wall 17. Supplemental gripping members such as star wheels 75 may be mounted in the respective medial slots on each leaf spring for rotational gripping engagement of the casing wall 11.

Operation The operation of the first form of the subject invention is believed to be readily apparent and is briefly summarized at this point. Initially, the cleaning device 13 is lowered by the cable 24 down the well casing 16 until the brush assembly 33 is positioned at the section to be cleaned. For operation, the device may be suspended either in a dry portion of the casing or, since the housing 14 is fluid tight, in the petroleum pool at the bottom of the well, not shown. The resilient springs are compressed inwardly by the casing wall 11 and the star wheels rotate along the wall so as to permit the housing to be raised and lowered smoothly in the casing 10. While the motor is off, the brushes remain gravitationally suspended in a retracted position as shown in FIG. 3. This allows ready and convenient manipulation of the device to attain the desired position in the casing.

The motor 25 is then energized and the cleaning assembly 33 commences to rotate, causing the cleaning members 34 centrifugally to swing or pivot radially outwardly until the ends of the brushes 53 forcefully engage the casing wall 11 and commence cleaning undesirable deposits therefrom. Rotation speeds of from about 1,000 to 3,600 revolutions per minute have been found suitable for removing sludge, tars, residues and other deposits which have accumulated on the casing wall and in the perforations 12, although other speeds are possible and within the scope of the invention. After the device has been operating a sufficient period of time in its initial position to accomplish its cleaning function, it is stopped to permit the brushes to retract and then is raised or lowered, usually in uits of stepped progression to allow cleaning of the remaining portions of the wall. It has been found that the cleaning rate may be as much as 5 to 10 feet of casing wall per minute, in a dry well. During operation, the leaf springs 65 and star wheels 75 grip the casing wall and prevent rotation of the housing 14.

In certain situations it may be necessary or desirable to employ a cleaning agent, such as an acid or solvent cleaner, in conjunction with the rotating cleaning members. Such a situation may arise when excessive deposits of tars and residues have formed on the casing wall 11, in the perforations 12, or in the pores of the surrounding strata, whereby by the pores and perforations become clogged and free percolation is prevented. When such conditions are found to exist, a sutficient amount of acid solution or the like may be introduced into the casing so as to effect the desired concentration of acid at the location of the excessive deposits. The cleaning assembly 33 is then lowered into the clogged section of the casing and the device is activated to cause the cleaning members to rotate against the casing wall. Thereupon, the rotating brushes cause the acid solution to circulate rapidly against the wall and to be thrown, forced or pumped centrifugally through the perforations into the oil bearing strata to dissolve the tars and residues and thereby to permit the desired and less viscous petroleum again to flow freely into the casing through the surrounding strata.

Operation of the casing cleaning device 13 using the second form of cleaning member 54 with star wheel 57 is substantially similar to that described above for the first form of cleaning member 34. The star wheels are oriented for rolling engagement with the casing Wall 11 during rotation of the shaft 36. Use of the star wheels have been found particularly effective when residue deposits have become hardened and encrusted. The points or teeth of the star wheels serve to bite or cut into such encrustments and break up the deposits.

From the foregoing, it is readily apparent that a casing cleaning device has been provided which is effective in rapidly cleaning the wall of a casing or other opening defined by a surface of revolution and which may be used either immersed in a pool petroleum or other liquid or in a dry section of the casing, borehole or opening. The device can be manipulated readily and conveniently in the casing and can be adapted to varying cleaning conditions by varying the rotational speed of the cleaning assembly to suit the conditions. The individual cleaning members are of simple construction and may be replaced easily and economically when necessary. Furthermore,

the cleaning assembly is rugged and therefore requires a minimum of maintenance. The concept of centrifugally forcing an acid solution or solvent into contact with the casing wall and through the wall perforations into the surrounding strata represents an entirely new approach which has proven very effective in removing excessive deposits of tars and other residues from the strata pores and the casing wall.

Although the invention has been herein shown and described in what are conceived to be the most practical and preferred embodiments, it is recognized that departures may be made therefrom within the scope of the invention, which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices and apparatus.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A device for cleaning a wall providing an inwardly disposed surface of revolution circumscribing an opening comprising a rotatable shaft adapted to be disposed within the opening, a plurality of pairs of cleaning members mounted on the shaft for rotation therewith, the members of each pair being aligned in diametric relation to the shaft, the pairs being in adjacent relation longitudinally of the shaft, and the aligned members of adjacent pairs being in substantially right angular relation to center the shaft in the opening during rotation of the shaft With the cleaning members in engagement with said surface each cleaning member being eccentrically pivotally connected to the shaft and adapted to pivot centrifugally outwardly of the shaft into cleaning engagement with the surface of the wall in response to rotation of the shaft.

2. A device for cleaning a wall providing an inwardly disposed surface of revolution circumscribing an opening comprising a rotatable shaft adapted to be disposed within the opening, and a cleaning member eccentrically pivotally connected to the shaft for rotation therewith and adapted to pivot centrifngally outwardly of the shaft into cleaning engagement with the inwardly disposed surface of the wall in response to rotation of the shaft, said cleaning member comprising an elongated metal cable, and means pivotally connecting said cable at one end to the shaft.

3. A device for cleaning a wall providing an inwardly disposed surface of revolution circumscribing an opening comprising a rotatable shaft adapted to be disposed within the opening, and a cleaning member eccentrically pivotally connected to the shaft for rotation therewith and adapted to pivot centrifugally outwardly of the shaft into cleaning engagement with the inwardly disposed surface of the wall in response to rotation of the shaft, said cleaning member comprising a resilient arm, said arm being pivotally connected at one end to the shaft; and a toothed member at the other end of the arm for rotation thereon, said toothed member being disposed in turning engagement with the wall surface during rotation of the shaft.

4. A casing cleaning device comprising a rotatable shaft, a resilient arm pivotally connected at one end thereof to the shaft for rotation therewith and adapted to pivot centrifugally radially outwardly in response to rotation of the shaft, and cleaning means on the other end of the arm placed in cleaning engagement with a casing wall during rotation of the shaft.

5. A casing cleaning device as defined in claim 4 wherein the arm comprises a spring, and the cleaning means include toothed means.

6. A casing cleaning device as defined in claim 4 wherein the cleaning means comprises a toothed member mounted at the other end of the arm for rotation thereon, said toothed member being disposed in turning engagement with the casing wall during rotation of the shaft.

7. A casing cleaning device comprising a housing, driven means within the housing including a rotatable shaft extending therefrom adapted to be disposed within a casing, cleaning means connected to the shaft for rotation therewith in cleaning engagement with the casing Wall, and means preventing rotation of the housing, said means comprising radially acting resilent means, and toothed means carried by said resilient means and continuously urged thereby into gripping engagement with the casing wall.

8. The device of claim 7 wherein said toothed means includes a toothed member mounted for rotation about an axis disposed transversely of the radially acting resilient means.

9. The device of claim 8 wherein said toothed member is a star wheel.

References Cited UNITED STATES PATENTS 588,830 8/1897 Jones 15-10414 608,418 8/1888 Bradley 15-10414 1,370,767 3/1921 Sperling 15-104.14 2,085,336 6/1937 Sandstone -104 2,181,306 11/1939 Osborn 15-104.14 2,187,845 1/1940 Tatalovich 166104 2,201,680 5/1940 Haynes 166104 2,609,182 9/1952 Arutunotf 175-104 JAMES A. LEPPINK, Primary Examiner. 

